chain has stretched ... time to replace?

[neil_p]

As per sheldon browns website I have measured my chain .... 10 links is 25.8mm .... which he says means time to replace chain and cogs.  However do rohloffs have more tolerance of worn chains?  Thus can the chainring/sprocket/chain give me some more miles?  How will I know when they really are too worn? 

[geocycle]

You can run a Rohloff chain until it falls off and you have run out of adjustment on the EBB.  However, you need to make a judgement of when to change in relation to wear of the sprocket and chainwheel.  For me this is about 5000 miles when I also reverse the sprocket and chain wheel. Another strategy is to rotate two chains every 2-3000 miles so they both wear evenly with the sprocket.  I start again each 10,000 miles (new sprocket, chain, probably chainring) but others have got double that.

[rualexander]

Yes, as long as you can tension your chain by the eccentric bottom bracket or sliding dropouts (you don't say what bike you have), you can just keep running the same chain until the sprocket gets very worn.
But if you don't want the sprocket/chainring to get worn out, then change the chain at the normal recommended stage.

[neil_p]

Cheers folks. Its a Thorn EXP with EBB. I've just got a new chainring/sprocket/chain with higher gear ratios (47x16) for fast day rides. I will keep my old parts (including the stretched chain) for laden touring, and use them as a set. The chain ring and sprocket had 7,000 miles then were reversed and have had another 5,000 miles. The stretched chain was new when I reversed the chain ring etc. I reckon I should get another 2,000 miles out of it.  I held by old sprocket up against the new one .... you'd be hard pressed to find any signs of wear which is quite remarkable!

[Mike Ayling]

My experience with derailleur gears is that the chain ring usually lasts three times as long as the cassette on account of it having 2.5 to 3 times as many teeth as the central sprocket on the cassette so I would not bother rotating the chain ring at the same time as the sprocket  unless someone here can convince me otherwise.

A problem that I have with our tandem is that with the chainring/sprocket ratio that we have we cannot use the full throw of the EBB there is only one adjustment available then its time for a new chain. I am considering trying a half link with our next chain.

Mike

[Post edited by Dan to remove off-topic query. That query can be seen here:
http://thorncyclesforum.co.uk/index.php?topic=11987.msg87200#msg87200 ]